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<TITLE>80386 Programmer's Reference Manual -- Opcode DAS</TITLE>
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<H1>DAS -- Decimal Adjust AL after Subtraction</H1>

<PRE>
Opcode    Instruction        Clocks   Description

2F        DAS                4        Decimal adjust AL after subtraction
</PRE>


<H2>Operation</H2>

<PRE>
IF (AL AND 0FH) > 9 OR AF = 1
THEN
   AL := AL - 6;
   AF := 1;
ELSE
   AF := 0;
FI;
IF (AL > 9FH) OR (CF = 1)
THEN
   AL := AL - 60H;
   CF := 1;
ELSE CF := 0;
FI;
</PRE>

<H2>Description</H2>

Execute DAS only after a subtraction instruction that leaves a
two-BCD-digit byte result in the AL register. The operands should consist
of two packed BCD digits. DAS adjusts AL to contain the correct packed
two-digit decimal result.

<H2>Flags Affected</H2>

AF and CF as described above; SF, ZF, and PF as described in <A HREF="appc.htm">Appendix C</A>.

<H2>Protected Mode Exceptions</H2>

None

<H2>Real Address Mode Exceptions</H2>

None

<H2>Virtual 8086 Mode Exceptions</H2>

None


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<B>up:</B> <A HREF="c17.htm">
Chapter 17 -- 80386 Instruction Set</A><BR>
<B>prev:</B><A HREF="DAA.htm"> DAA Decimal Adjust AL after Addition</A><BR>
<B>next:</B><A HREF="DEC.htm"> DEC Decrement by 1</A>
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